Somatosensory- and Motor-evoked Potential Monitoring Without a Wake-up Test During Idiopathic Scoliosis Surgery. An Accepted Standard of Care

Study Design: This was a retrospective study of 500 patients undergoing corrective surgery between 1987 and 1997 for spinal deformity caused by idiopathic scoliosis.

Objectives: To report the sensitivity and specificity of somatosensory-evoked and neurogenic motor-evoked potentials monitoring and the requirements for an intraoperative wake-up test for all idiopathic scoliosis surgeries at a single institution.

Summary Of Background Data: Intraoperative monitoring is recommended for use during corrective spinal surgery. Accepted monitoring standards and requirements for an intraoperative wake-up test are still debated.

Methods: The study group consisted of 500 patients undergoing corrective surgery for idiopathic scoliosis between 1987 and 1997. All patients were monitored using somatosensory-evoked and neurogenic motor-evoked potential techniques, using a standard protocol developed at this institution.

Results: The false-positive rate (significant data change without postoperative neurologic deficit) was 0.014% (n = 7). The true-positive rate (degradation of data that met warning criteria, with a corresponding postoperative neurologic deficit) was 0.004% (n = 2). No false-negative results (normal data during with a postoperative neurologic deficit) were seen. The sensitivity of combined somatosensory-evoked and neurogenic motor-evoked potential data in predicting neurologic status was 98.6%, and the specificity of normal data predicting normal findings in a neurologic examination was 100%.

Conclusion: Combined somatosensory-evoked and neurogenic motor-evoked potentials monitoring during idiopathic scoliosis surgery represents a standard of care that obviates the need for an intraoperative wake-up test when reliable data are obtained and maintained.